Sliding door roller repair

This is a photo of the roller I modified in order to keep it moving.
I can't find any identifying marks on the roller, or the door, which is custom built 8 1/2 feet tall by 4 1/2 feet wide.
It was installed 35 years ago and we cannot find anyone from the original builder to help.
I didn't measure the roller before I put it back together but it is about 2 1/2 inches long.